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This specification extends the events and features defined in DOM Events Level 3.
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Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)
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Goals
UI Events builds on the event model defined in DOM Level 3 Events (and also DOM4). Features in scope for this specification are:
- Additional Keyboard event properties to allow for physical key location scenarios
Keyboard Events
This section extends the KeyboardEvent interface defined in DOM Level 3 by adding methods for querying the keyboard state without requiring a Keyboard event to be dispatched, and by providing locale information during the dispatch of a Keyboard event.
Interface KeyboardEvent
- static DOMString queryKeyCap()
-
Given a
code
corresponding to a key on a standard keyboard and a [[!BCP47]]locale
, thequeryKeyCap
method returns the character that would be generated if that key were pressed (without modifiers or any special modes in effect) while the specified keyboardlocale
is in effect. Assuming thatlocale
matches the user's physical keyboard, then this value will match the value printed on the keycap (the cap placed over the key switch) on the keyboard.This method is intended to be used primarily for the writing system keys because the values generated by these keys vary based on the current keyboard locale. For keys not classified as writing system keys or for keys that do not generate printable characters, this function returns the
code
for the key (i.e., it returns that same value that was passed in). Note that the'AltRight'
key always returns 'AltRight', even though some locales have this key labeledAltGr
.Dead keys should return the combining accent character.
The value 'Undefined' is returned if the
locale
's keyboard does not contain the key specified bycode
.- DOMString code
- The code for the key, as defined in the [DOM Level 3 KeyboardEvent code Values] spec.
- optional DOMString locale
-
If specified, this should be a [[!BCP47]] tag (like 'en-US') that identifies the keyboard layout in which to interpret the
code
parameter.
If not specified, then thecode
value is interpreted in the context of the 'en-US' locale.
- readonly attribute DOMString locale
-
The
locale
DOMString
attribute contains a [[!BCP47]] tag indicating the locale for which the keyboard originating the event is configured, e.g."en-US"
. Thelocale
MAY be the empty string when inapplicable or unknown, e.g. when this information is not exposed by the underlying platform.Note:
locale
does not necessarily indicate the locale of the data or the context in which it is being entered. For example, a French user often might not switch to an English keyboard setting when typing English, in which case thelocale
will still indicate French. Nor can it be used to definitively calculate thephysical
orvirtual
key associated with the event, or the character printed on that key.The un-initialized value of this attribute MUST be
""
(the empty string). - static DOMString queryLocale()
-
Returns the current keyboard locale as a [[!BCP47]] string, such as 'en-US' or 'fr-FR'. The value returned here is encoded the same as the value in the KeyboardEvent
locale
attribute.
Calling queryKeycap
for various keys
queryKeyCap('KeyA') =>'a'
Default locale is 'en-US' queryKeyCap('KeyA', 'en-US') =>'a'
queryKeyCap('KeyA', 'fr-FR') =>'q'
queryKeyCap('Digit2', 'en-US') =>'2'
queryKeyCap('Digit2', 'fr-FR') =>'é'
('\u00e9') queryKeyCap('IntlRo', 'en-US') =>'Undefined'
Key doesn't exist in US keyboard queryKeyCap('IntlRo', 'ja-JP') =>'ろ'
('\u308d') queryKeyCap('Quote', 'nl-US') =>'´'
('\u0301') Combining accent queryKeyCap('Quote', 'ru-RU') =>'э'
('\u042d') queryKeyCap('Backquote', 'en-US') =>'`'
queryKeyCap('Backquote', 'ja-JP') =>'Backquote'
Non-printable Halfwidth/Fullwidth Mode key queryKeyCap('Space') =>'Space'
Non-printable queryKeyCap('ShiftLeft') =>'ShiftLeft'
Non-printable
The value returned by queryKeyCap
is suitable to be presented to a user (for example, in a
preferences dialog that allows the user to customize the key mappings) unless the returned value is
'Undefined'
or if it is equal to the code
that was passed in to the method.
Getting the current keycap for 'KeyA'
queryKeyCap('KeyA', queryLocale())